The fabrication of a semiconductor device involves a plurality of discrete and complex processes. In certain processes, it may be advantageous to heat the workpiece so that the process achieves the desired result. One method of heating the workpiece is through the use of heat lamps. For example, tungsten halogen light bulbs may be used to emit energy toward the workpiece. In other embodiments, LED lights may provide the thermal energy.
Power from tungsten halogen bulbs is emitted at wavelengths ranging from about 400 nm to 2600 nm, with the peak being at approximately 1000 nm. At wavelengths between 600 nm and 1800 nm, the emitted power is at least half the maximum emitted power. The distribution of energy may vary for other heating elements.
In certain embodiments, the workpiece is disposed on a workpiece support, and is heated by heating elements disposed below the workpiece. In other words, the workpiece support is disposed between the heating elements and the workpiece. Thus, the workpiece support may block some of the light from reaching the workpiece. To mitigate this problem, the end effector may be constructed from a transparent material, such as clear quartz. Tests have shown that about 88% of the light energy passes through a workpiece support constructed from clear quartz.
However, at elevated temperatures, such as 500° C., the workpiece support may affect the local temperature of the workpiece. For example, the portion of the workpiece directly above the workpiece support may be 50° C. cooler than the other portions of the workpiece.
Therefore, it would be advantageous if there were an apparatus that could support the workpiece without adversely affecting the passage of light energy to the workpiece. It would be beneficial if such an apparatus could be used on existing systems.